Matter is anything that has mass, volume, and occupies space. It is the stuff that makes up the universe, from the smallest atoms to the largest stars.

Matter can be in different states, or phases, including solid, liquid, gas, and plasma.

Examples of matter include:

* A rock is an example of a solid. It has a fixed shape and volume and cannot flow.

* Water is an example of a liquid. It has a definite volume but can take the shape of its container.

* Air is an example of a gas. It has no definite shape or volume and can spread out to fill its container.

* Fire is an example of plasma. It is a hot, ionized gas with no definite shape or volume.